[FFmpeg-devel] [PATCH 2/2] avformat/hls: Don't strdup non-null-terminated string

[Andreas Rheinhardt]

Steven Liu:
> 
> 
>> 2020年3月22日 上午7:28，Andreas Rheinhardt <andreas.rheinhardt at gmail.com> 写道：
>>
>> Andreas Rheinhardt:
>>> If an URI indicated that the data protocol was in use, it would be
>>> copied into a temporary buffer via strncpy(dst, src, strlen(src)),
>>> thereby ensuring that the trailing \0 would not be copied, despite dst
>>> being uninitialized. dst would then be av_strdup'ed, leading to
>>> potential segfaults.
>>>
>>> The solution to this is simple: Don't copy the URI in the temporary
>>> buffer at all, instead av_strdup it directly.
>>>
>>> This fixes a -Wstringop-truncation warning emitted by GCC 9.2.
>>>
>>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>>> ---
>>> This is honestly untested, as this is not covered by FATE.
>>>
>>> libavformat/hls.c | 7 +++----
>>> 1 file changed, 3 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/libavformat/hls.c b/libavformat/hls.c
>>> index 1f58e745a7..fc45719d1c 100644
>>> --- a/libavformat/hls.c
>>> +++ b/libavformat/hls.c
>>> @@ -403,8 +403,7 @@ static struct segment *new_init_section(struct playlist *pls,
>>>                                         const char *url_base)
>>> {
>>>     struct segment *sec;
>>> -    char *ptr;
>>> -    char tmp_str[MAX_URL_SIZE];
>>> +    char tmp_str[MAX_URL_SIZE], *ptr = tmp_str;
>>>
>>>     if (!info->uri[0])
>>>         return NULL;
>>> @@ -414,11 +413,11 @@ static struct segment *new_init_section(struct playlist *pls,
>>>         return NULL;
>>>
>>>     if (!av_strncasecmp(info->uri, "data:", 5)) {
>>> -        strncpy(tmp_str, info->uri, strlen(info->uri));
>>> +        ptr = info->uri;
>>>     } else {
>>>         ff_make_absolute_url(tmp_str, sizeof(tmp_str), url_base, info->uri);
>>>     }
>>> -    sec->url = av_strdup(tmp_str);
>>> +    sec->url = av_strdup(ptr);
>>>     if (!sec->url) {
>>>         av_free(sec);
>>>         return NULL;
>>>
>> Ping.
> Looks ok.
>>
>> - Andreas
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> 
> Thanks
> 
> Steven Liu
> 
Applied, thanks.

- Andreas